Tubular core assemblies which have a hollow cylindrical core member of paper board material and an annular end member of plastic material within each opposite end portion of the core member are known, see for example U.S. Pat. No. 5,236,141 issued Aug. 17, 1993, U.S. Pat. No. 5,595,356 issued Jan. 21, 1997, U.S. Pat. No. 5,615,845 issued Apr. 1, 1997, U.S. Pat. No. 5,725,178 issued Mar. 10, 1998 and U.S. Pat. No. 5,829,713 issued Nov. 3, 1998, the contents of which are hereby incorporated herein by reference.
U.S. Pat. No. 5,615,845 and U.S. Pat. No. 5,829,713 mentioned above are particularly concerned with tubular core assemblies intended for mounting on chucks having radially movable portions which are movable radially outwardly to engage the inner surface of a tubular core assembly and on chucks which are movable under axial pressure into engagement with the ends of the tubular core assembly. Some of the tubular core assemblies described in these two prior patents are also suitable for use with chucks having a single key which engages in a notch in the tubular core assembly.
In the printing industry, paper rolls have until recently usually been mounted on chucks by means of equipment which is manually controlled. However, equipment which automatically mounts paper rolls on chucks without requiring manual control is now being provided in press rooms. When such automated equipment is used, chucks without keys are moved under axial pressure into engagement with the ends of a tubular core assembly, because it is difficult to mount a paper roll on chucks with keys with such automated equipment.
For various reasons, it is advantageous to use with such automated equipment tubular core assemblies which comprise a hollow cylindrical core member of paperboard material with an annular end member of plastic material within each opposite end portion thereof. As described in the previously mentioned prior patents, each annular end member is provided with at least one radially-projecting lug adjacent an end thereof which is engaged in a lug-receiving notch in the core member to facilitate transmission of torque and axial chuck pressure from the end member to the core member. The prior patents also teach that each annular end member should preferably be provided with a pair of notches at diametrically opposite positions for receiving a key of a roll supporting chuck.
When automated equipment is used to mount paper rolls on axially movable chucks without keys in a press room, it has been found to be necessary for the chucks to engage the ends of the tubular core assemblies with very high continuous axial or radial pressure for efficiently transmitting torque thereto, especially when very heavy paper rolls are used, for example paper rolls having a weight when fully wound of about 3,000 lbs. or more.
It has been found that, when tubular core assemblies with end members as described above are subjected to such very high continuous axial or radial pressure, the transmission of such pressure through the annular end members to the core member may cause the core member to become distorted under continuous static and/or dynamic loads. Since the core members of heavy paper rolls may be of considerable length, for example about 5 feet or longer, such distortion may cause serious problems with rolls unwinding at high speed during a printing operation, especially if the rolls are slightly out of round.
It is therefore an object of the invention to provide a tubular core assembly comprising a core member with annular end members which is more suitable for use with automated roll mounting equipment.